Research on the Characteristics of Moderate Plant Shape of Tobacco Variety Zhongchuan 208 in Shandong Tobacco-growing Areas

To explore the plant type characteristics of the new flue-cured tobacco variety Zhongchuan 208 as a moderate plant shapes tobacco in Shandong tobacco-growing areas, the agronomic and economic traits, as well as the quality differences of middle and upper leaves after curing, were investigated in three different growth types (Z1, Z2, Z3) of Zhongchuan 208. The classification criteria for the three growth types were specified as follows. Z1: plant height >140 cm, effective leaf number >24; Z2: plant height 130~140 cm, effective leaf number 22~24; Z3: plant height <130 cm, effective leaf number <22. The results showed that there were no significant differences in the proportion of high-grade tobacco and average price between Z2 and Z3, but both were significantly higher than those of Z1. The total scores for appearance quality evaluation of middle and upper cured leaves of Z3 were 12.63% and 4.30% higher than those of Z1, respectively, and 3.88% and 2.11% higher than those of Z2, respectively. The coordination of the conventional chemical components of the middle and upper leaves was optimal in Z3, mainly reflected in the higher contents of total sugar and reducing sugar in Z3, and both the total sugar/reducing sugar ratio and sugar/nicotine ratio were within the appropriate ranges. The total score of sensory quality of middle and upper leaves of Z3 was the highest, which was 5.14% and 11.41% higher than that of the lowest treatment, respectively. The comprehensive evaluation of the tobacco leaves from the three treatments indicated that the comprehensive quality of Z3 was the best. Therefore, the suitable plant type characteristics of Zhongchuan 208 as a moderate plant shapes tobacco in Shandong tobacco-growing areas are represented by Z3, with the specific agronomic indexes plant height of 123.24±1.78 cm, effective leaf number of 20±0.82, stem circumference of 8.92±0.48 cm, middle leaf length of 69.97±1.26 cm, middle leaf width of 30.14±1.43 cm, upper second shed leaf length of 44.92±2.00 cm, and upper second shed leaf width of 20.28±0.98 cm.